Edmund Gunter was responsible for introducing the words cosine and cotangent to the world as well as producing a seven figure table of logarithms of sines and tangents. Gunter also manufactured and used a precursor of the slide rule, called the Gunter scale. As if this were not enough Gunter also invented a device called Gunter's chain which was used for surveying, he published a work on navigation, studied magnetic declination and was the first to observe the secular variation. Whilst not one of the most original mathematicians Gunter had a very applied mind, and he contributed a number of practical uses for mathematical techniques and devices.
Gunter was born in Hertfordshire in Southern England in 1581. He attended Westminster School in London as a child and then carried on his education at Christ Church in Oxford where he remained until 1615. Gunter graduated initially in 1603 with a bachelors degree and then he gained a masters in 1605 and finally he obtained a divinity degree in 1615. After his ordination Gunter became the rector of St George's Church, in Southwark, London. He retained this position until his death aged 45 in 1626. From 1619 until 1626 Gunter was also the Professor of Astronomy at Gresham College, London.
In 1620 Gunter published Canon Triangulorum or the Table of Sines and Tangents. This book was a list of logarithms of sines and tangents to seven decimal places. To aid in calculations using these figures Gunter made a precursor to the slide rule. This was called Gunter's scale and it gave the user the ability to multiply the logs together using a single scale on a copper rod in conjunction with a pair of dividers. Logarithms were plotted on this rod on a straight scale and multiplication could be carried out rapidly by the addition or subtraction of different lengths using the dividers. This device was extensively used by seamen as a navigation aid and its description was published in his 1624 book Description and Use of the Sector, the Crosse Staffe and Other Instruments. The slide rule as we now know it is essentially two Gunter scales which are slid one against another. The advantage of Gunter's scale was that it could be used to provide a rapid answer of sufficient accuracy for navigation at sea. For more accurate results lengthy calculations would have to be entered into and these were often unnecessary for the job in hand.
In 1623 Gunter published New Projection of the Sphere which looked at navigation and the magnetic effects of the Earth thereon. In 1624 Gunter published a book on a number of sundials he had installed in Whitehall, this was at the direct request of the future Charles I. In 1626 Gunter died at the age of 45 in London.
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